Electrode for hydrogen peroxide

Campanella et al. [1] Superoxide radical polyphenols Sulfite Ascorbic acid Wine Superoxide dismutase (SOD), or tyrosinase, or sulfite oxidase, or ascorbate axidase/in a gel-like kappa-carrageenan membrane sandwiched between a cellulose acetate membrane and a dialysis membrane Amperometric Pt electrode for hydrogen peroxide (for superaxide determination)/ +650 mV vs. Ag/AgCl/ Amperometric oxygen electrode (for the rest)/-650 mV vs. Ag/AgCl... 

F. Ricci, A. Amine, C.S. Tuta, A.A. Ciucu, F. Lucarelli, G. Palleschi and D. Moscone, Prussian Blue and enzyme bulk-modified screen-printed electrodes for hydrogen peroxide and glucose determination with improved storage and operational stability, Anal. Chim. Acta, 485(1) (2003) 111-120. 

The biosensor [1] was obtained by coupling a transducer (an ampero-metric electrode for hydrogen peroxide) with the superoxide dismutase enzyme immobilized in kappa-carrageenan gel. Sandwich the gel containing the enzyme between a cellulose acetate membrane and a dialysis membrane. Secure the whole assembly to the electrode with an O-ring (Fig. 12.1). 

ChemicaUy Modified Electrode for Hydrogen Peroxide Measurement by Reduction at Low... 

Giomo, M., Buso, A., Fier, P., Sandon G., Boye, B., Famia, G. (2008,). A small-scale pilot plant using an oxygen-reducing gas-diffusion electrode for hydrogen peroxide electrosynthesis. Electrochimica Acta, 54(2), 808—815. 

Regarding applications involving surface modification with carbon nanotubes or other nanomaterials, similar considerations can be applied, for example, with chitosan/carbon nanotube-modified electrodes for hydrogen peroxide sensing or glucose biosensing. 

Low-molecular-weight redox mediators have been used in the construction of choline electrodes for hydrogen peroxide detection. A sensor for choline and acetylcholine was described using anodic detection of hexacyanoferrate (III) in solution. Ferrocene and tetracyanoquinodimethane"" were also used in the construction of choline electrodes. The use of redox mediators facilitates the electron transfer but leads to the system complications. 

A. Eftekhari, Aluminum electrode modified with manganese hexacyanoferrate as a chemical sensor for hydrogen peroxide. Talanta 55, 395 402 (2001). 

I.L. Mattos, L. Gorton, T. Ruzgas, and A.A. Karyakin, Sensor for hydrogen peroxide based on Prussian blue modified electrode improvement of the operational stability. Anal. Sci. 16, 1-5 (2000). 

Tkac J, Ruzgas T (2006) Dispersion of single walled carbon nanotubes. Comparison of different dispersing strategies for preparation of modified electrodes toward hydrogen peroxide detection. Electrochemistry Communications 8 899-903. 

The potential of the electrode is set in the diffusion limiting plateau region of hydrogen peroxide oxidation. Therefore the concentration of hydrogen peroxide at the surface of the electrode is also zero. Furthermore, there is no hydrogen peroxide in the bulk of the solution that is stirred. Therefore, its concentration at the gel/solution boundary is also zero. Thus, the boundary conditions for hydrogen peroxide are... 

We report here the results obtained by the use of a screen-printed electrode as electrochemical probe to be coupled with a microdialysis fibre for continuous glucose monitoring. The most significant advance is represented by the introduction of a mediator (PB) as the principal factor for hydrogen peroxide measurement. The improved operational stability observed with the PB-modified screen-printed electrodes has demonstrated that these sensors could serve as tool to be applied for the continuous monitoring of many analytes. The application to diabetic care seems to be the most promising and advantageous area in which to test these sensors. 

Dow-Huron cell — Electrochemical cell for hydrogen peroxide production. A diaphragm-divided cell employing a carbon chips-PTFE composite as cathode material fed with air. At the anode oxygen is developed at, e.g., a platinized titanium electrode. 

It is possible that some acetate radicals are formed by the direct discharge of the ions as, it will be seen shortly, is the case in non-aqueous solutions but an additional mechanism must be introduced, such as the one proposed above, to account for the influence of electrode material, catalysts for hydrogen peroxide decomposition, etc. It is significant that the anodes at which there is no Kolbe reaction consist of substances that are either themselves catalysts, or which become oxidized to compounds that are catalysts, for hydrogen peroxide decomposition. By diverting the hydroxyl radicals or the peroxide into an alternative path, viz., oxygen evolution, the efficiency of ethane formation is diminished. Under these conditions, as well as when access of acetate ions to the anode is prevented by the presence of foreign anions, the reactions mentioned above presumably do not occur, but instead peracetic acid is probably formed, thus,... 

In non-aqueous solutions the Kolbe electrosynthesis takes place with high eflSciency at platinized platinum and gold, as well as at smooth platinum, anodes increase of temperature and the presence of catalysts for hydrogen peroxide decomposition, both of which have a harmful effect in aqueous solution, have relatively little influence. The mechanism of the reaction is apparently quite different in non-aqueous solutions and aqueous solutions in the former no hydroxyl ions are present, and so neither hydroxyl radicals nor hydrogen peroxide can be formed. It is probable, therefore, that direct discharge of acetate ions occurs at a potential which is almost independent of the nature of the electrode material in a given solvent. The resulting radicals probably combine in pairs, as in aqueous solution, to form acetyl peroxide, which subsequently decomposes as already described. ... 

CCEs have also been used in conjunction with enzymes. Glucose oxidase was encapsulated within the methyl silicate (or silica)-graphite composite [216, 220]. Reduced oxygen from the enzymatic reaction results in the production of H2O2, which is oxidized at the electrode. Palladium and rhodium catalysts have been added to the electrode to help lower the over voltage required for hydrogen peroxide oxidation [219, 221]. Glucose oxidase and horseradish peroxidase have been simultaneously entrapped within a CCE for a biosensor that does not require a... 

Figure 42. Electrode potential diagram for hydrogen peroxide system.

In a different approach, HRP-modified electrodes were used for the enzyme-catalyzed cathodic reduction of hydrogen peroxide. Very stable and active systems could be obtained for hydrogen peroxide sensing [162]. 

Figure 8 is a possible redox cycle occurring in an amperometric sensor for hydrogen peroxide involving enzyme-wiring of a typical enzyme (Horseradish peroxidase, HRP) with polyaniline. HRP immobilized on the electrode surface can be oxidized by H2O2 to compound I that contains an oxyferryl centre with the iron in the ferryl state (Fclv = O), and a porphyrin 7r cation radical, followed by further direct (mediatorless) electroreduction of compound I at the electrode surface to the initial HRP state [106], The electrode is considered as an electron donor. 

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